Embarcation on the 'Zahra'

On the 10th of March, I had to get up at 4.00 a.m. because they’d booked me on the 7.00 a.m. flight from Cairo to Luxor. I was picked up on time at 4.45 a.m. by the same car and driver but a different guide. We made good time to the airport, this time to the small domestic terminal nestling next to the international terminal. There was a crowd queuing to check in but my guide went to what I think was an unmarked check-in and quickly got the formalities dealt with for this, my first Egyptair flight. We then said goodbye. I spent a while writing a word file to incorporate in the blog, then I had a cup of tea and croissant at the small café. Although fairly basic, waiter service was provided.

When the flight was called, I passed through security to the waiting area. A bus drew up immediately outside. We boarded the bus which then drove in a ‘U’ to the aircraft waiting not 50 yards from where we got on! In fairness, the main internal road ran just outside the departure lounge so I suppose they’d decided to use the bus rather than having people dicing with death trying to cross the road but it’s the shortest ride I’ve ever had.

My seat number was 20A so I started to walk back along the cabin from the front entrance then I discovered that, on this aircraft (an Embraer 170, I think), the front row is numbered 20! In fact, I was in the tiny club class section. It was a short journey of just over an hour to my destination, Luxor, so there was only time for a drink and a bread roll. Most of the country we overflew was desert but, as we approached Luxor, we could see the Nile and the green swathe on either side which the river irrigates.

We landed safety and the business class disembarked first. I was surprised to find there was a separate transfer bus laid on for the business class passengers. This time, the journey was a few hundred yards. I met my guide – a very well-spoken, smartly-dressed young man - and we waited for my checked bag which only took a few minutes to arrive. Then we walked to the car and driver and set off for the short drive (around 10 kilometres) to Luxor City. It was only a little after eight and embarkation time on the boat was shown as noon, so I was worried as to what I’d do but my guide was unruffled.

The city was something of a surprise. The unkind first thought was “A bit like Blackpool, but less tasteful”. The proximity to tombs and temples means they’ve been catering for tourists for over a century and tourists have clearly been arriving in large numbers. When we got to the Nile, I was amazed to see rows of Nile cruisers, moored up to five deep all along the Corniche. Most of the shops seemed to be cafes of one sort or another or selling tourist souvenirs. We carried on south for a few kilometres, past a series of slightly more upmarket resorts and private moorings for Nile cruisers, until we came to the one for the Oberoi ‘Zahra’.

A short driveway at right angles to the road led past a security hut to a car park flanked by a grassed area. Moored at the river’s edge was the impressive-looking Hotel Ship ‘Zahra’. It was only 8.50 a.m. but I was welcomed aboard and seated in the Club Lounge area with a 'Welcome Drink' of locally-produced sparkling wine with hibiscus. The passengers from the previous cruise were still breakfasting, prior to leaving. One beaming English lady assured me “You’re in for a treat!”. Tapan, the Manager, dealt with the check-in formalities and invited me to take breakfast with the departing passengers, but I declined. He assured me my room should be available soon and that the wait will be no more than an hour – in fact it was much less. After a conducted tour of the facilities on the boat, I was shown my spacious and well-appointed room. During the morning, the other passsengers arrived and at 12.30 we all enjoyed an excellent A La Carte lunch in the dining room, prior to our afternoon excursion by road.

Pictures of 'Zahra'.

Canal Zone, Egypt

A year ago I visted the Panama Canal (see my posts, starting with Panama). Although the Frenchman, Ferdinand de Lesseps, started the Panama Canal it was America that finished it. De Lesseps had previously achieved fame through the building of the Suez Canal, which had been a huge commercial success (although a large number of men lost their lives during construction). So I was keen to see the Suez Canal.

The Suez Canal links the Mediterranean to the Red Sea, saving almost ten thousand miles compared with the journey round the Cape of Good Hope. There are no locks - it's a sea-level canal, the longest such in the world and the third longest canal of any type. In the south, Suez marks the start of the waterway heading north through the Bitter Lakes, using as much natural formation as possible. North of Qantara, the long, artificial 'cut' extends to the Mediterranean at Port Said. Although the channels are being widened to accommodate simultaneous bi-directional movements, at present traffic is one way at a time.

We left Cairo heading east for Suez. It took some time to shake off the city - of the 75 million (and rising) inhabitants of Egypt, 20 million of them are in Cairo. Having left Cairo, we came to massive new housing developments - tall apartments reminiscent of southern China. This is New Cairo, very much 'a work in progress'. A myriad high-voltage pylon routes run parallel to the road. Comprehensive electrification of the country has taken place, presumably in the wake of the controversial hydro-electric project at Aswan.

The wide dual-carriageway passes through arid desert. It’s not the smooth, rolling dunes you might picture but a pock-marked landscape looking as if a mighty army of moles have been at work.

Road discipline in Egypt is, to say the least, unusual. On this 2-lane dual carriageway, traffic travels in either lane at any speed, overtaking or undertaking as convenient or swerving from lane to lane to make better progress. It’s not for the faint-hearted. There’s an almost continuous procession of heavy six-wheel lorries, each invariably towing a massive six-wheel trailer.

Eventually we come to the industrialised city of Suez. Egypt is self-sufficient in oil and Suez is the location for one of the refineries. The massive refinery site seems to have at least three fractionating columns for distilling petrol – not particularly modern-looking plant but clearly effective since petrol is very cheap in Egypt. We don’t go into the city proper but park near the Stadium overlooking the Gulf of Suez. The sun is bright but the wind off the water keeps the temperature down. After a few photographs of the Gulf, we set off north by road, passing through a rather depressing area of multi-storey apartments and crossing the railway near the refinery sidings.

Once again, the signs of modernisation accompany us, in the form of a number of medium-voltage overhead power lines. It's not just power; each community has a massive water tower assuring water supplies and there’s evidence of major drainage schemes as well. Frequent radio towers testify to a developed communications system. There are also cellphone masts – Egyptians seem to be addicted to mobile ‘phones as much as the rest of the world. The most unlikely buildings sport satellite dishes for television reception. Egypt has certainly made great strides in developing a modern infrastructure. However, when you look at any of the local buildings, they tend to be in a state of amateur lack of completion – a sort of ‘anything goes’ philosophy common in the third world. Even the least-complete dwellings, where you would imagine nobody yet lives, seem to have satellite dishes. Presumably the tenants consider a television service is more of a priority than, say, doors and windows. Something of this philosophy extends to road vehicles as well. Many are so battered that it seems improbable that they’re able to move at all.

From the road, we can see the railway paralleling our course on our right. I’ll refrain, with some difficulty, from discussing the lower-quadrant semaphore signalling still in use. Click for railway pictures.

The Bitter Lakes are further east and not visible. We’re back in the desert but irrigation means there’s a lot more green than on the first leg of our trip from Cairo to Suez. About 15km out of Suez, we pass the road junction leading to the Ahmed Hamdi tunnel under the Canal. Egypt only holds a narrow strip of land on the east of the Bitter Lakes, then you’re into Israel. The road tunnel provides the most direct route from Cairo to Israel. Egypt keeps careful watch on its neighbour to the east. We pass one large military compound with a large radar aerial pointing east, presumably on the lookout for attacking Israeli jet aircraft. We continue north, passing through the outskirts of Ismailiya. Modern bridges carry us over a wide irrigation canal and a double-track railway line.

Further on, we make a stop at a café with a large garden area. There’s a special room where one of the young waiters in jeans and T-shirt has a large stock of waterpipes which he prepares as ordered by customers. The ‘sheesha’ (which I learn is its correct name) is an integral part of Egyptian café life. I just have a cup of tea (Yellow Label tea bag, no milk but with sugar and in a polystyrene cup – the Egyptian way). There’s another road crossing into Israel at the Ferdan Suspension Bridge over the Canal. The road to Port Said passes under the bridge approach road which is carried on improbable-looking tall concrete piers.

Then, we see our first ship on the Canal, looking as if it’s sailing across farm land – the canal itself is out-of-sight. Ships are heading north at present. Click for ship pictures. Before we come to the next ship in the northbound convoy, we pass a passenger train from Port Said heading south. The next ship is the ‘Maersk Tukang’, with the hull in the characteristic pale blue colour of the Maersk Line and triple-decker containers on deck. This ship is followed by a black-hulled Hanjin Line vessel, also with three layers of container on deck. The following green-hulled China Shipping Lines vessel has containers stacked on deck seven high in places! I know there's a lot of weight inside the hull from the containers loaded in the hold, but it all looks very top-heavy. Further north, there's another Maersk Line vessel which appears to be called 'Sealand Slings' with container stacks 6-high in places. The 'Nedlloyd Drake' only balances the deck containers three high. Two more high voltage power lines march towards us from the west and continue on the east bank but they're not carried over the canal on tall pylons as is often the case. Instead, elaborate switchyards near the shore on either bank suggest an underwater cable connection.

As we approach Port Said, the city's maritime nature is announced by a tough-looking motor cruiser beached in a wave of concrete at the side of the road. We turn off the main road and head for the docks. Port Said is an important container-handling port and more container cranes are visible on the other side of the canal at Port Fouad. On our side, the modern ocean-going tug 'Oil Traveller' is moored. Symbols painted on the hull indicate that she's fitted with Bow Thrusters for improved manoevreability. There's a rather nice little building in the middle of the road junction near the entrance to the docks - I presume it's a disused port security office. Modern security is provided by an elevated watchtower with a single guard of the type that proliferate all over the country. A few more photographs and it's time to set off back towards Ismailia.

The first vessel we see as we set off for the south is the 'Hanjin Paris' which we spotted on the way in, followed by 'Maersk Tukang'. Behind her is green-hulled 'CSAV MARUMBI'. Apparently, the shipping line is called 'CSAV' but I've no idea where the Marumbi comes from. 'Rickmers Doha' is next, grey painted with only a couple of containers on deck but she sprouts a variety of derricks and deck cranes so that she can load and off-load her own cargo. A non-container ship follows, fitted with four deck cranes. For some reason, two of the massive hatch covers are partly open. 'Lissa Topic' follows - again non-container and with four deck cranes. The next vessel (with two deck cranes) has a remarkable deck cargo - lots of blades for big wind turbines. The next vessel is even more extraordinary. As far as I can see, it's moored off the main channel and appears to be an engineering vessel. There are two vertical piles at the rear which can be jacked down, presumably to hold the vessel firm when working. There are two deck cranes, of different types plus a massive girder framework extending from the bow with cables extending into the canal. It seems likely that this is an excavator bucket for dredging.

The bigger cities form 'Governorates' for administrative purposes. At the boundary of Port Said Governorate, some distance from the city, we pass through a highly-decorated toll gate. Travelling in this direction, I spot signs of an earlier accident. Something has hit one of the concrete supporting pillars and, insufficiently reinforced, it has crumbled, allowing the roof structure to partially collapse. The whole mess has been shored up with wooden scaffolding and life goes on.

We continue and, near Ismailia, take the direct road to Cairo. As we get nearer to Cairo, I'm surprised at how much industry there is. A lot of the factories are modern, large and in the heavy heavy engineering sector. I'm told that Russians have make significant purchases of Egyptian industry.

Our route takes us past the airport and into the city. This time, the traffic is heavy and progress is a lot slower. For a while, an elderly tram system shares our route.

Back at the Conrad, the Executive Lounge is fairly busy with people having drinks and eating the light meal on offer. Having enjoyed a snack, I buckle down to the first version of this blog and an early night - I've to be up early in the morning!

Pictures of the Canal Zone.

[Re-issued with additions on 10th, 11th, 12th and 28th March 2009]

Into Egypt

Boarded the aircraft (a British Airways 747-400) on time. Cabin staff very hospitable. For some reason, we were over half an hour late taking off. The journey to Cairo was less than 5 hours - short compared with some of my trips - so I didn't find it tedious. They served quite a reasonable dinner and I watched the 'Casino Royale' remake which I'd not previously seen. Cairo is currently two hours ahead of the UK so it was a quarter to midnight when we got off. I was surprised to find the travel company 'meeters and greeters' were 'Airside'. I easily found the man from Somak (who've provided this part of the trip) and he directed me to his colleague, Hossam, who walked me to Immigration, saying he'd meet me the other side. This time, I'd got the Visa in the U.K. (although you can buy them on arrival) so I was quickly into the baggage hall. My one checked bag was on 'Priority' and it soon appeared. Then it was outside to find the driver and car (an XJS). Although the airport road can get jammed, since it was just after midnight we sailed through on this occasion.

Security in Cairo is quite tight. The entrance to the Conrad Hotel was barred by an electric gate until the security man had checked the boot and examined the underside of the car with a 'mirror-on-a-stick'. On entering the hotel, my bags were X-rayed and I had to pass through a metal detector. Hossam checked me in and then said goodbye, saying I'd be picked up from reception in the morning at 8.30. I made my way (slightly wearily) to room 2333. The lift didn't move until another guest got in and activated it with his credit-card sized electronic room key. I realised that, as another security measure, you can't get far without your room key.

In common with a lot of city centre hotels catering for business travellers, the Conrad has a number of dedicated 'Executive Floors'. At Cairo, it's floors 20, 21, 22, 23, 24. The middle floor, 22, contains a private Lounge for use by guests on the executive floors. This is to stop business guests feeling hard done to when coach loads of tourists check in having paid highly-discounted room rates. I let the Bell Boy show me how the various things worked. He also showed me the views over the city and the Nile from the private balcony. By the time I was sorted out and in bed, it was 2.00 a.m. The bed was very comfortable and I was soon asleep. I felt fairly refreshed when I got up on Monday. I found the complimentary breakfast in the Executive Lounge very adequate and was in Reception just before 8.30. It was a little while before I found my young guide, Marko, because he'd been ringing my room from somewhere and, of course, I wasn't there. We met up with the driver and XJS from the previous night and set off on a trip to see the Canal Zone.

Pictures of the Conrad Hotel.

"The Game's Afoot!" (again)

I'm at Heathrow, off again. This time, a fairly modest itinerary, taking in just Egypt and Jordan.

Regular readers may remember that I've made a brief visit to Egypt once before, in February 2005. This was described in "Round the World Two". I was very impressed with the ancient Egyptian civilisation and determined to return one day. Well, that day is today.

I'm in the lounge at Heathrow, waiting for my British Airways flight to Cairo. This is my first departure from the new Terminal 5. It's also the first time on one of these jaunts that I've checked in on the Internet at home so, on my arrival, all I had to do was find the 'Bag Drop'. As usual, the time spent navigating security tends to put me in a bad mood - I respond badly to queuing and being bossed around. But I suppose it wasn't too bad (being relatively quiet on a Sunday afternoon).

My flight leaves from the Satellite terminal so I make my way by the driverless underground train from T5 to its Satellite. I'll spare you the details except to say rubber wheels on a concrete base with a central guide rail. Then I made my way to the Gallery Lounge, set up in the eaves and looking out onto the apron on two sides. It was raining on the way to Heathrow by road but, as I write this, the sun has come out and it all looks more cheereful. There are lots of Internet workstations and they work, so that creates a good impression. There's time to grab an orange juice and a bowl of vegetable soup, make this post, then I'm away to the Gate for my flight. I'll write more when I can.

Photographs

Heathrow.

Princes End

In 'Visiting Signalboxes' I described how, in the late '50s and early '60s, I managed to visit (and unofficially operate) a number of mechanical signal boxes in the West Midlands. Most of this write-up is from memory - notes I made at the time are lost or mislaid.

Back in the '50s, the Stour Valley Line from Birmingham to Wolverhampton made a triangular junction with the double-track Princes End Line. The boxes controlling the triangle were Tipton and Bloomfield Junction (both on the Stour Valley Line) and Tipton Curve Junction (on the Princes End Line). The next box was Princes End, then the line continued to Wednesbury, where it joined the South Stafford Line.

I worked the adjacent box at Tipton Curve when the signalling was still absolute block but I didn't get to work Princes End box until after Wolverhampton Power Box had opened. Princes End became a fringe box to the Power Box and trains to and from the Stour Valley were 'sent' and 'arrived' by Train Describer. The train describers at fringe boxes were made by Standard Telephones and Cables and were largely electro-mechanical, using crossbar switches. Crossbar switches were used in telephone switching for a short period, before reed relay and electronic designs took over. I spent some time studying the design of the train describer equipment at Princes End. There was usually plenty of time in between trains for study.

By the time I knew Princes End, the line down to bank to Wednesbury had been singled and was operated by Electric Token. Originally, it had been double. I believe the line was singled partly because of subsidence in one area of the embankment, probably caused by an underground fire. In mining areas such fires seemed fairly common. At the time, there was also what seemed to me a rather perverse fashion for reducing track maintenance costs by singling double track sections. I was never convinced that this idea was justified, taking into account the signalling complication at each end of the single line where it rejoined normal double track and the operational problems of having to wait for a train in one direction to clear before a train could pass in the opposite direction.

The box was of standard L&NWR construction, with the frame nearest to the track. Behind the frame, set in the floor, were a number of Annett's keys which could be released to allow a train to work at one of the private sidings controlled by Princes End. I think I only remember Austin's Siding being used and that infrequently. The display for the Train Describer to Wolverhampton sat on the block shelf.

The electric token machine for the single line to Wednesbury sat on a small table on the back wall of the box, next to the desk for the Train Register Book. Princes End was the only box I worked with electric token working, so I found this of interest and studied the operating principles. This relatively-simple equipment had brought considerable safety to the operation of single lines but, like any system invented by man, could be defeated by not sticking to the procedures. The head-on collision at Abermule in 1921 (see Wikipedia article) is an example of this.

There was a level crossing at the Wednesbury end of the box, controlled from a gate wheel which I found heavy to operate. Beyond the level crossing were the long-derelict passenger platforms. I think the passenger service was discontinued in the 1930s.

When the electrification of the Stour Valley was in progress, the Princes End Line was often used as a diversionary route for passenger trains at weekends. I can't remember details, but 'Sunday Stroll to Stafford' describes one trip I made.

I was at Princes End Box one day when the line was used for an emergency diversion. Mid-morning, there was a Scottish express from Birmingham to Glasgow, IS61, which was booked to run along the Stour Valley Line. One day, the North Stour became blocked (probably the day a freight tried to leave the down sidings at Spring Vale before the road was set. The steam loco ended up 'down the bank' and wagons were strewn around. Wish I'd seen it). 1S61 had already passed Winson Green (where it could have been diverted onto the Soho Road Line) so 'Control' decided to divert it onto the Princes End Branch. I don't know where it went afterwards - probably Rugeley then Trent Valley Line to regain its proper route at Stafford. To my surprise, '1S61' popped up on the train describer so I was able to send a 'four-beater' (express) to Wednesbury and extract the single line token (an overgrown 'lollipop'). These were handed directly to the loco crew from the narrow landing outside the front of the box principally used for window cleaning. There was no 'loop' as sometimes used to simplify the exchange. As 1S61, headed by an English Electric 'Type 4', roared towards the box, I was horrified at the speed the driver was maintaining and I had visions of either breaking a finger or dropping the token. In fact, I made the exchange OK but I still remember my fear!

There's a series of fairly technical articles on the electrical signalling controls starting with Princes End Electrical Controls (Part 1).

London Underground - Traction Power Distribution

White City, pictured during an Engineering Possession.

These notes on London's Underground Railways are taken from training material prepared by Ford Electronics Limited, with permission. Ford Electronics produce Tunnel Telephone systems for use on underground railways. This description applies to most lines, but there are local differences.

Introduction

London Underground uses d.c. traction power distribution from a series of substations at the relatively low voltage of around 630 volts. The conductor system consists of conductor rails laid along the track route allowing power to be picked up continuously by the train through its shoegear equipment. The positive conductor rail laid outside the running rails and the negative conductor rail laid between the running rails are supported on porcelain insulators at a maximum pitch of around 4.3 metres.

At turnouts, crossings, expansion gaps, isolator switches and section gaps the conductor rails are broken. Ramps at the start and end of conductor rail section lift the train collector shoes onto the rail or lower the shoes from the rail. The length of the gap depends upon the track feature. At turnouts and crossings, the gap is variable. Expansion gaps are normally 1 metre, provided every 246 metres on the surface and every 606 metres underground. Isolator switch gaps are normally 1 metre and Section gaps 15 metres.

The outer conductor rail is normally about 450 volts positive with respect to earth and the inner conductor rail in between the running rails is normally about 180 volts negative with respect to earth. The d.c. power is not directly earthed and the actual voltage to earth on each conductor rail will depend upon the insulation resistance. During wet weather on exposed lines, around 300 volts on each conductor rail is possible. Intentional indirect earthing through Bleed Resistors (see below) is provided at certain locations to establish the conductor rail to earth voltages during non-leaky conditions.

Source of traction power

Originally, London Underground produced its own power at generating stations like Lots Road, which no longer exists. Nowadays, power is taken from the National Grid at a number of sites at either 11kV or 22kV 50Hz, but London Underground currently retains the capability to generate power at a peak-lopping gas turbine installation at Greenwich, which is only used as emergency supply if the grid fails. As necessary, this high voltage a.c. power is distributed to Traction Sub Stations. To provide the necessary supply security Traction Sub Stations frequently have alternative sources, usually at 11kV 50Hz.

Traction Sub Stations

Transmission losses at 630 volts d.c. are relatively high so, to avoid excessive voltage drop, Traction Sub Stations (TSSs) have to be located quite close together. Originally, Traction Sub Stations were staffed but they are now remotely controlled from a power control room at a central London site.

At each Traction Sub Station, the incoming three-phase high voltage supply is transformed down and rectified (using fan-cooled semiconductor rectifiers) to provide the earth-free d.c. supply for the conductor rails. A typical rating for a single rectifier unit is 1500kW. Substations are normally provided with two or more rectifiers. Often, one rectifier will power the two roads in one direction, a second will power the two roads in the other direction. Circuit breakers allow individual roads to be discharged.

The conductor rails are divided into sections extending from one Traction Sub Station to the next. Each section is double-end fed with d.c. from rectifiers at both Traction Sub Stations, to further minimise voltage drop, particularly when more than one train is in a section. A simplified diagram of the arrangement is shown in Figure 2.1 below.

The practical arrangement of a typical Traction Sub Station with two rectifiers is illustrated in Figure 2.2 below.

The substation has two d.c. busbars linked or isolated by a coupling breaker. Each rectifier and each road supplied is associated with a circuit breaker. At most TSSs, the coupling breaker is normally closed so that both rectifiers and all four roads are connected together to minimise voltage drop.

Track Paralleling Huts

At Track Paralleling Huts, the conductor rails are broken to form a section gap, but normally contactors are closed to connect together all the positive conductor rails and all the negative conductor rails. Again, the aim is to reduce the voltage drop as a number of rectifiers can contribute current to each section. The arrangement is shown in Figure 2.3 below.

Sectionalisation

As described above, at most Traction Sub Stations the coupling breaker is normally closed so that the conductor rails are effectively continuous from section to section. Since the conductor rails are not directly earthed, an earth fault from one side of the supply to earth (for instance, on a traction motor or collector shoes) does not prevent the system from operating. But a second earth fault on the other side of the supply will cause the overcurrent protection to operate. If all the coupling breakers were closed, a second earth fault could propagate a shutdown along the whole length of the line, involving a large number of passengers.

To limit this fault propagation, London Underground introduced a technique called 'Sectionalisation' where a number of traction sections are connected together (to help minimise voltage drop) but the coupling breakers are intentionally open at the Traction Sub Stations defining the ends of that Sectionalisation section.

Bleed Resistors

In the absence of leakage currents to earth from the conductor rails, the voltage of each conductor rail with respect to earth is defined by a potential divider of bleed resistors added at each end of the Sectionalisation Section from each conductor rail to earth. The conventional values are 220 ohms (positive rail) and 110 ohms (negative rail).

Related articles in this Blog

Fourth Rail Electrification

Tunnel Telephone System

In tunnel sections of the system, a Tunnel Telephone system is provided to facilitate traction discharge and voice communication between the driver and Line Controller. Traction trip and speech is provided over two bare copper alloy wires carried, one above the other, on pairs of porcelain insulators supported on metal brackets fixed to the tunnel wall, usually on the right-hand side in the normal direction of travel. The insulators are generally provided every 6 metres along the tunnel so as to keep the wires about 115mm apart. The wires are positioned so as to be accessible by leaning from the driving cab window of a train. The general appearance of a single-bore deep tunnel is shown in Figure 2.4 below.

Where it is necessary for the tunnel wires to be carried across to the opposite tunnel wall, Over Track Crossings (OTX) are provided using cable. Where different sections of tunnel wire need to be interconnected, or equipment introduced, cabling is used and test boxes with sliding disconnection links may be provided to facilitate fault-finding.

Related posts on this website

All my posts on London Underground can be found here.

This topic is continued at London Underground - Traction Power Distribution (2).

[Bleed resistor values transposed, link to part (2) added 11-Apr-2021]

German Railway Signalling

This is a fairly superficial introduction to German railway signalling, intended to illustrate how different countries have evolved different solutions to the same basic problem of moving trains safely around the network.

Each European country has its own national variant traditional signalling system. Broadly, they may be divided into two types:-
- Route signalling, as in the U.K., where the specific route set is indicated to the driver
- Speed signalling, as in Germany and most European countries, where the maximum safe train speed is indicated to the driver, but the particular route set is not indicated.

In Germany, early colour light signals are according to system 'HV' using red, yellow, green and white lamps. More modern installations use system 'KS' where the signal lamps are supplemented by speed indicators for both Main and Distant signals.

The Hauptsignal (Main signal) is a stop signal. To allow sufficient braking distance for a train to stop at an adverse signal, each Main signal is preceded by a Vorsignal (Distant signal). This is a warning signal which may be passed when showing a restrictive aspect. The sequence of Distant signal, Main signal suffices where main signals are at least 1300m apart, otherwise a Distant signal is provided on the same post as the previous Main signal and, where this does not provide sufficient braking distance, also on the Main signal previous to that.

The heading photograph shows two Hauptsignal (main signal) at the north end of Mannheim Hauptbahnhof. Signal P004 on the left controls northbound departures from platform 4 and signal P003 on the right applies to platform 3. I believe the 'double red' is to prohibit passing the signal for shunting purposes, as well as prohibiting departure. The green lamp is above the red signal lamps. Below are two diagonal white lights which, when lit, authorise shunting movements beyond the red signal. Below the shunting signal is the yellow lamp forming part of the main signal allowing the 'green over yellow' aspect. When 'green over yellow' is displayed, the speed indicator at the top of the post (backed by a triangular sighting board) indicates the authorised reduced speed, in km/h divided by ten. Mounted lower down the post is the Distant signal indicating the aspect of the next Main signal.

This Distant signal is provided halfway along platform 3 at Mannheim, serving as the warning for signal P003, visible in the background. To indicate that the signal is less than the braking distance from the Main signal, a white light is displayed to the left of the signal. There will have been a previous warning signal at the full braking distance. The distant signal has two 2-lamp clusters, each showing Yellow or Green. The picture shows the 'double yellow' warning. When the main signal is displaying a proceed indication, the Distant displays a 'double green'. Where necessary, the 'green over yellow' indication can be given, indicating that the following Main signal is showing proceed at less than the line speed.

This picture shows two more Main signals at the north end of Mannheim Hauptbahnhof. Signal P002 on the left controls northbound departures from platform 2 and is showing 'double red'. Again, there are green and yellow lamps, plus a shunting signal and a numeric speed indicator at the top of the post. The cluster of three lights forming an 'A' is the 'Substitution signal'. These white lights, when lit, authorise a train to pass a defective Main signal which cannot be cleared. Lower down the post is the Distant signal for the next main signal, with a white light to indicate that it is less than the full braking distance from the Main signal.

Signal P001 on the right applies to platform 1. The grouping of lamps is a little more compact and the Shunting signal has additional lamps. The Main signal is displaying 'green over yellow' for proceed at reduced speed, as indicated (in this case) by the '5' in the speed indicator at the top of the signal for 50km/h. Mounted lower down the post is the Distant signal showing 'double yellow' indicating that the next Main signal is displaying 'stop'.

An elevated shunting signal is shown on the extreme right, applying to southbound moves on platform 4. Note the climbing brackets attached to the post to allow access to the signal head and the reflective red and white identification panel attached to the post to make the signal more visible to an approaching train. Another shunting signal applying to northbound moves on platform 4 can be seen, just behind the approaching 'ICE' train. A similar signal is mounted on the platform canopy of platform 3.

A snatched (rather fuzzy) picture of a Main signal as we passed at speed. Main signal at the top of the post. Below this, a shunting signal displaying two white lights diagonally and below this the yellow main aspect (to permit 'green over yellow' to be displayed. The separate cluster of three (yellow) lights forming a 'V' is the Caution signal. When illuminated, it allows a failed main signal to be passed. Below this, is the familiar diagonal pair of 2-lamp clusters of a Distant signal. Lower down the post is the signal number plate and the red and white reflective identification panel. There is no access ladder but the construction of the post presumably facilitates climbing. There are, however two landings with handrails to assist the maintainer - one by the main signal cluster, one by the distant signal. Finally, notice the two signalling equipment cases at the foot of the post.

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Another Main signal, near Frankfurt. All the standard aspects are provided but, in addition to the Main signal speed indicator at the top of the post, there is a Distant speed indicator (displaying yellow numbers) beneath the Distant signal.

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A main signal mounted on a bracket, presumably to improve sighting, on the approach to Frankfurt. This is a 'KS' system 'Combination' signal. The three Main lamps (red, yellow, green) are arranged in an 'A' to serve as a combined Main and Distant signal. It displays 'single red', 'single yellow', 'single green' or (when the Distant Speed indicator is lit) 'flashing green'. There is a Speed indicator above the Main signal and a Distant Speed indicator below the signal. The red and white identification panel indicates a Main signal - the yellow triangular identification panel is used in the 'KS' system to indicate a Distant signal.

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A final example of a bracket signal, near Frankfurt Hauptbahnhof. This appears to be a 'KS' system Distant with yellow and green signal lamps and a Distant Speed indicator below.

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As can be seen, conveying speed information to drivers can result in quite complex trackside equipment so the trend is now towards 'Cab Signalling' where speed information is presented in the cab and there may be no fixed signals along the route. But that's another story.

The pictures in this article are taken from my collection on German Railways.

Information on railway signalling in Germany is taken from 'European Railway Signalling', published by A & C Black for the Institution of Railway Signal Engineers (ISBN 0-7136-4167-3).

High Speed Trains

Having been so beastly about our rail service in 'Brave New Railway', it's only fair that I comment again when I have a good journey. The only problem is that the good journey was on an 'Inter City Express' (ICE) service in Germany.

I'd flown to Frankfurt with two people from my client to attend a meeting in Mannheim. Terminal 1 at Frankfurt Airport is linked to stations serving both main and suburban rail lines. The ICE service offered the fastest connection to Mannheim and we'd time to buy a ticket for three at the multi-lingual ticket machine before descending to the platform. Clear displays on the platform showed train details and the layout of the train (including catering facilities). Announcements in English and German apologised for the 5 minute late arrival (most of which had been recovered by the time we got to Mannheim).

The Siemens-built ICE train was warm, the decor both inviting and relaxing and we readily found suitable seats. There's a pleasant air of spaciousness - the design benefits from the Berne Loading Gauge which is more generous than the British Loading Gauge. In addition, our 'Pendolinos' and 'Super Voyagers' are designed to tilt, resulting in a cabin narrower at the ceiling than the floor to ensure a tilted body remains within the loading gauge. The ticket inspector was friendly and chatted in English to us. Toilets were clean and everything worked. The ICE isn't cheap, but you have the option of travelling on a regional train at about half the price. We arrived in Mannheim suitably impressed.

The next day, when our meetings were finished, we travelled from Mannheim to Frankfurt itself. A pleasant, right-time experience. We were a little puzzled when the train first stopped at Frankfurt Airport and then, after a pause of a few minutes, reversed to travel on to Frankfurt Hauptbahnhof. Later that day, we returned to the airport, this time using the suburban 'S-Bahn' service - a far more basic service for which we paid far less. All-in-all, a satisfying experience.

It must be about 25 years since I was last in Frankfurt (visiting the German consultants employed on the Taiwan Trunk Line Electrification Project) and the railway scene is considerably changed. Then, 'DB' stood for Deutsche Bundesbahn which was a self-regulatory body. This has been turned into a public limited company, Deutsche Bahn AG, regulated by the Federal Railway Office Eisenbahnbundesamt (EBA).

The heading photo shows our ICE train on arrival at Frankfurt Hauptbahnhof. More pictures.

An Apology

My friend Chris pointed out a number of mis-spelled place names in my post 'Halfex to Blackpool'. I've corrected these errors (with a tinge of sadness - what I'd described as "wonderfully named Bashalls Sidings" becomes the prosaic Balshaws Sidings but see the Post Script below). If only those were the only errors!

As I say in '9:17 a.m. to Birmingham' "Would that I had been more diligent in recording the passing scene - my only defence is that I was young and just could not imagine that it would all be swept away". Many of the notes which I did make at the time are mislaid (it is some time ago!) but I decided to carry on and write down what I can remember and hope that more of the original notes eventually come to light. Not very likely until I give up work, I'm afraid. The more you try to remember details from that long ago, the less sure you become. For instance, I'm not certain now whether that train mentioned above was timed to leave at 9.17 or 9.18. I've mused about how difficult it is to get things right in 'Work in Progress'.

As far as recording the railway scene goes, I was usually just passing through on a train, frantically trying to make track and signalling diagrams as that was my principal interest at the time. Most of my exploits were on former L.M.S. lines, so the problem of identifying signal box names when passing at speed was easier than on many lines. The Great Western, for instance, produced a cast nameplate of often astonishing length which was fixed to the front of the box, facing the track. This could make it very difficult for a passenger to correctly identify the location. The L&NWR used individual cast letters, six inches tall, screwed to a board, again on the front of the box.

Initially, the L.M.S. used a similar arrangement but A. F. Bound, the Signal & Telegraph Engineer, had been impressed by the Great Central practice of fixing a nameboard at each end of the box - much easier to sight from a train. After some experimentation, the standard L.M.S. signal box nameboard appeared in 1935, using six inch cast letters fixed to a 9-inch high wooden board with a three-quarter inch rounded bead. For more details, refer to the excellent book 'A Pictorial Record of L.M.S.Signals' by L. G. Warburton, published by Oxford Publishing Company in 1972 (available, for a price, on the second-hand market).

L.M.S. pattern signal box nameboard photographed at Brereton Sidings in 2007

Railways could also be quite obstinate in the spelling they adopted. I've written about the signalbox at Sedgeley Junction. The nearby Sedgley Road West leading to the town of Sedgley both get by with only two 'e' in the name, but the railway invariably used three.

I shall continue to strive for accuracy and, no doubt, will continue to fail but I hope that something will be left to entertain or inform. To quote the Duke of Wellington (during an attempted blackmail attempt regarding letters he had written to a courtesan - I had to look it up, I knew the saying but not its origin): "Publish and be damned!"

Post Script

After I'd published this apology, my friend Chris confessed that, when he'd checked further, he'd discovered that the name 'Bashalls Sidings' was, in fact, correct.

Review of the Year, 2008

Last year I picked the word 'Antarctica' to describe the most significant experience of the year. This year, the word has to be 'Burma'. Yes, I know we're supposed to call the country 'The Union of Myanmar' but somehow 'Burma' seems to fit better. My first visit to Burma was the first stage of 'Round the world Five' in March 2008. That one trip gave me a lifetime's worth of experiences.

After visiting Rangoon (and a trip on the 'Circle Line' railway), I headed north for a river trip on the Irrawaddy. Rudyard Kipling wrote "Burma is like nowhere you have ever seen" and I found that's still true (My picture shows the massive golden pagoda of the Shwedagon in Yangon).

Leaving Burma with its friendly people and the 2,000 ancient temples of the Bagan Plain, my next stop was Las Vegas which provided something of a contrast, to say the least. I didn't take to the city but I loved the Grand Canyon and Hoover Dam and spent some time at the State Railway Museum at Boulder City.

Then, on to the Yucatan Peninsula in Mexico, where I looked at the Mayan city at Chichen Itza. The next country was Cuba. Havana and Trinidad were both quite special. I found a surprising number of deteriorating steam locomotives in two Havana 'museums' but the working steam trip on the Valle de los Ingenios line was cancelled because of locomotive failure. Instead, I did the trip on a diesel railcar (and got a short drive at the end!). Finally, I went to Panama. I enjoyed looking at the history, travelling on the newly-rebuilt Panama Canal Railway and, particularly, studying the operation of the Panama Canal. All the places on that trip were interesting, but it's my impressions of Burma that stay with me.

On my return, I booked to return to Burma in August 2008 for a different river trip but, as so often happens, Fate intervened. On 2nd May 2008, Cyclone Nargis hit Myanmar, causing terrible damage and loss of life. The ship I'd booked on was severely damaged and was taken out of service for repairs and a major refit.

Back in England, weekend footplate work at Peak Rail, the Battlefield Line and the Museum of Science and Industry in Manchester kept me busy. I've posted various write-ups, including a typical 'Driving Turn at Peak Rail'. I visited Tyseley Railway Museum at the end of June for the 'Tyseley 100' celebrations, meeting many old friends.

July was quite busy, with a visit to RSC Stratford to see 'Hamlet' with David Tennant, 'Day out with Thomas' events at the Battlefield Line and an Old Locomotive Committee (OLCO) meeting. Now 'Lion' has returned to Liverpool, OLCO activities are restricted, but I was observer, once again, at 'Lionsmeet 2008' which was held at Butterley.

I was involved in Peak Rail's 'Warring Forties' weekend in August (my picture shows me sporting a 'tin helmet') and attended my first 'Organathon' at Brewood Parish Church, then back to the Battlefield Line for a visit by 'Ivor the Engine'.

Although my August river trip had been cancelled, I went back to Burma at the beginning of September to meet my new friends and find out more from them about the ongoing relief work. My own journey continued to Mandalay and then to fascinating Inle Lake. Lots of temples to explore, culminating in a trip to Shan State and the 2,000 temples at mysterious Kakku. I returned to Yangon, said goodbye to my friends and flew to Chiang Rai in Thailand where I stopped at the Anantara Resort located at the 'Golden Triangle'. A day learning about elephants at the 'Elephant Camp' proved a moving (and occasionally wet) experience. Next, I made a rather undignified entrance into Laos on a small ferry in the pouring rain and joined a two-day cruise on the Mekong River. This proved totally absorbing and participating in the 'Big Brother Mouse Book Party' at a remote village school was quite emotional. Like most visitors, I was charmed by the old capital, Luang Prabang, before flying on to the more Western, but still distinctly Laotian, modern capital of Vientiane. Then, back home via Bangkok, pausing in Dubai. The city of Dubai didn't appeal, I'm afraid, but two nights at a resort out in the desert gave me a new experience.

In October, I was involved in three of the 'Day out with Thomas' events at the Battlefield Line in October (my picture shows 'Thomas' in one of his many 'incarnations'). We were very lucky with the weather for these 'Thomas' events. In December, I was rostered for a couple of days on the footplate with the 'Santa Specials' at Peak Rail and, again, the weather was fairly kind.

In the run-up to Christmas, over 80 members of Brewood Civic Society visited Brewood Hall and, a few days later, Warwickshire Baroque performed a Christmas Concert at the Hall (my picture shows the concert in progress and the 'Christmas Concert' report includes a video of part of the performance). Both events helped to raise funds for the relief work in Myanmar.

Well, these are some of the highlights of the year but there was lots more, too. When I'm at Brewood, my dog, Tai, and I are inseparable. In amongst everything else, I managed to work more-or-less full time during the year. In view of the fact that the world's financial systems appear to be in meltdown, I'd better plan to carry on working in 2009! It's a good thing I (mostly) enjoy work.

Finally, thanks and best wishes for the New Year to all my friends.

Brave New Railway

After the criticism heaped upon Network Rail following engineering overruns in the past, in December 2008 Network Rail were quick to applaud their own "massive achievement" in finally completing the 9,000,000,000 pound sterling upgrade of the West Coast Main Line.

It was a genuine tragedy that the crash of a light aircraft near Little Haywood in Staffordshire closed the line on 2nd January 2009, immediately following re-opening after the Christmas engineering closures. Almost as soon as the line was re-opened, a train brought down the overhead at Watford, causing widespread cancellation and delay on 5th January 2009. On Tuesday, another train brought down the overhead at Bletchley and, for good measure, workmen shorted an overhead cable at Nuneaton. Again, there were delays and cancellations. The passengers had to be evacuated from one train at Wembley after enduring freezing conditions for over a hour. And then, on Wednesday, a train brought down the overhead at Kenton, resulting in cancellation of all services for the day.

On Thurday 8th January 2009 I had to travel to London for a meeting and I approached the station at Wolverhampton with some trepidation (and notes about possible alternative journeys via Chiltern Line to Marylebone and Arriva Cross Country to Paddington). Of course, the beginning of the year has brought the usual above-inflation fare increases (up to 11% for some fares) which the Train Operating Companies justify as the price for improving the railway. At Wolverhampton I was assured that trains were currently running normally and, indeed, the 09:45 departure was only 8 minutes late away at 09:53. This was caused by the late arrival of the down train forming my departure. We were Birmingham New Street in at 10:15, out at 10:19, Birmingham International in at 10:30, out at 10:31, Coventry in at 10:40, out at 10:41. We managed to make up a little time on the journey to London, arriving Euston at 11:38, only 4 minutes late on schedule.

I wasn't quite so lucky on my return. A preceding departure from Euston had failed on the down fast, requiring us to be swopped to the down slow to get past the recalcitrant. This resulted in a 20 minute late arrival. I suppose the prospect of making up time was dashed by Network Rail's decision to impose a 110 m.p.h. temporary speed restriction south of Rugby.

I believe there were further problems on Friday and it's estimated that over 250,000 passenger journeys have been affected in just 5 days. A Network Rail spokesman gushed that the chaos was due to an "extraordinary list of unfortunate incidents". The grown-ups amongst us probably think that phrase is a fair description of what we expect in normal life. I'm ashamed, humiliated and disgusted that, in railways as in apparently most activities, my country appears an impotent laughing-stock.

MIC - Brakes

The Mutual Improvement Classes of the old steam railways still continue for today's preservation volunteers. This is one of a series of posts from notes of talks given by Jan. To find them all, select label 'MIC'.

1. History and theory

Before the coming of railways, horse drawn wagons didn't need much braking. Such brakes as were provided tended to be a piece of wood which rubbed against the tread of a wheel. The increased weight and speed of trains meant that braking became important. It's hard work to start any wheeled vehicle because Sir Isaac Newton's laws of mechanics say that you need to supply energy to change the state of rest. The required energy is proportional to the product of the mass and the square of the speed change. But you may have noticed that, with a railway vehicle, it takes much less effort to keep it moving. In theory, Newton's laws say a body should keep going at uniform speed without any further work being done. But in any practical vehicle, there's friction between the turning and stationary parts of the vehicle. This rubbing generates heat which uses up the energy of motion until the vehicle stops (the energy of motion or kinetic energy is converted into heat energy), unless you keep supplying energy to make up these frictional losses.

Steam locomotives were so powerful and the frictional losses relatively so small, that it's possible for an engine to haul lots of wagons. Thus, energy of motion is large because the mass is large. The unexpectedly high speed of early trains means that the energy of motion is large, by the square of the speed. In other words, a train travelling at 20 mph has four times the energy of motion of the same train travelling at 10 mph. That train will not stop until all the energy of motion has been converted into heat. This is why driving a locomotive is different from, say, driving a car. The energy of motion of 7029 'Clun Castle' is proportional to mass times square of speed. At 15 mph, the 135 ton locomotive has the same energy of motion as a 1-ton car travelling at 175 mph.

So braking technology suddenly became important, particularly on trains conveying passengers. A guard or brakeman would travel on the last vehicle, provided with some form of handbrake which could be applied as required. Great Western locos still have a distinctive-toned separate brake whistle to allow the driver to let the guard know that braking assistance is required. To increase the braking effort available, every fourth or fifth coach would be provided with a brakeman and handbrake. This simple arrangement gave rise to some terrible accidents either when the driver lost control of the train or when a coupling broke on a rising gradient and the rear part of the train rolled backwards towards the following train. Armagh 1889 was one of the most famous accidents of this class. Even today, catch points are provided on rising gradients so that breakaway wagons rolling backwards will be deliberately derailed, rather than letting them accelerate towards a following train.

Towards the end of the nineteenth century, the Railway Inspectorate gave up its long-standing campaign seeking voluntary co-operation by the railway companies in improving braking systems and changes made it a legal requirement for passenger trains to have an 'automatic' brake. The three requirements were that this brake be effective on all vehicles on the train, be capable of application by driver, guard and (through the communication cord) passengers and be automatically applied to both halves of a divided train. Back in 1875, brake trials of competing designs, carried out at Newark, had shown that designs based on the use of vacuum or compressed air were capable of meeting the requirements. Both systems came into widespread use, principally the vacuum system in Britain and the Empire and the air system elswewhere. British railways now use the air brake, but in the steam era the vacuum brake was the most common and that's the pattern we will look at in more detail in section 4 below.

2. Scotches

If vehicles have no operative brake, they must be properly secured when left on a siding, by the use of wooden scotches. One scotch is placed on either side of a wheel so as to prevent movement in either direction. Alternately, an unbraked vehicle may be coupled to an adjacent vehicle which has effective handbrakes.

3. Handbrakes

The simplest braking system is the handbrake found on most wagons. A cast iron brake shoe can be forced against the tyre of one or more wheels by pressing a long brake lever downwards. When the handbrake is applied on a moving vehicle, the friction between brake block and tyre as the wheel revolves generates heat, slowing the movement. The cast iron is softer than the steel tyre, so the brake block is worn away with use. Once stopped, an applied brake will make it harder for the vehicle to move again. Adjustments are provided in the brake linkage to allow wear in the brake block to be compensated, but eventually the complete block needs to be replaced. The block is usually fixed to the rigging with a wedge shaped cotter secured by a split pin, to facilitate exchange.

To apply the brake, the lever is dropped, pressed down hard and secured in that position by pushing a pin (attached to the wagon by a chain) through one of a series of holes. The harder the brake lever is pushed down, the greater the retarding force. A wooden 'brake stick' is used to apply the desired downward pressure. The square end of the brake stick is placed over the brake handle and the end of the brake stick is located securely under a convenient part of the wagon (such as the spring), allowing you to push down the rounded end of the brake stick with one hand and insert the pin with the other. Do not use a shunting pole as a lever, or be tempted to climb on the brake lever and use your weight to depress the brake lever.

To release the brake, press down the brake handle as described above and remove the pin, carefully remove the pressure and lift the handle fully upwards so that it can be located on the ledge provided.

On old wagons, the brake handle only works the brake blocks on one side of the wagon. On more modern wagons, pressing down the brake handle on either side applies the brake blocks to all four wheels. Either way, the brake handles on both sides of a wagon must be 'picked up' before you attempt to move it. Remember, when leaving a wagon on a siding you must apply the handbrake before you uncouple it from the engine and, when collecting a wagon, it must be coupled to the engine before the handbrake is removed.

Handbrakes may be applied by other means such as a short lever or a wheel. Usually, the wheel is turned clockwise to apply the brake ('screw down') and anti-clockwise to release the brake, but check each vehicle. On goods brake vans and the guard's compartment of passenger stock, a horizontal wheel mounted at waist height on a column rising from the floor within the vehicle is usual. This type of brake generally has a pawl and ratchet arrangement so that, once the brake is applied, it cannot be released accidentally. To release the pawl, turn the brake wheel slightly clockwise so that the pawl can be lifted up to its released position. Before applying the brake, make sure the pawl is flipped down so that it can work against the ratchet and hold the brake applied. Locomotive handbrakes are often on a column similar to a guard's brake, but with an L-shaped handle in place of a wheel. Where a chain is provided, this should be slipped over the handle after applying the brake, to prevent accidental brake release.

4. The Vacuum Brake

The automatic or continuous brake provides a brake on each vehicle which can be applied by the driver, the guard or passengers. When passengers operate the communication cord (now called the PCD, Passenger Communication Device), a partial brake application is made to alert the driver. The term 'automatic' refers to the fact that, if a train becomes divided, the brakes will automatically be applied to both halves.

Let's look at the vacuum brake in more detail. The brake blocks and brake rigging are similar to a handbraked vehicle (and may be worked by a co-acting handbrake lever or wheel) but are connected by a vertical piston rod to a piston which can move up and down in a sealed brake cylinder. This piston is made airtight in the cylinder by a rolling ring or slipping band gasket around the edge of the piston. Where the piston rod passes out through the bottom of the brake cylinder, there is also an air-tight gland. The lower section of the cylinder is connected by pipes to the flexible vacuum hoses on either end of the vehicle. If these hoses are open to the air, then there is atmospheric pressure underneath the brake piston. If the brake has been previously manually released (described below), then there's also atmospheric pressure above the piston. The weight of the brake piston and its piston rod causes the piston to fall to the bottom of the brake cylinder and this RELEASES the brake blocks, allowing the vehicle to be moved. The upper and lower parts of the brake cylinder are interconnected through a one-way ball valve which lets air flow from the upper to lower part, but prevents airflow from lower to upper half.

Before moving off, the driver will create a partial vacuum in the train pipe which runs the length of the train, with adjacent vehicles connected using the flexible vacuum hoses ('bags'). The locomotive sucks air out of the train pipe so as to reduce the pressure in the brake pipe considerably below atmospheric pressure. The partial vacuum created is registered on brake gauges on the locomotive and in the guard's van or compartment. A reading of '0' represents atmospheric pressure, '21' is the degree of vacuum used by most locomotives and '25' is the higher vacuum used by ex-Great Western locomotives.

These numbers are in units called 'inches of mercury' since Torricelli discovered a simple way of creating an almost perfect vacuum and measuring it in terms of the height of a column of mercury in a closed-end glass tube. The units are often shown as 'ins/Hg' where Hg is the chemical symbol for mercury (it's an abbreviation of the latin name for mercury). Bigger numbers represent a more-perfect vacuum.

Air is sucked out of the lower part of the brake cylinder and the ball valve allows air to be extracted from the upper part of the cylinder as well, so that the train pipe and both sides of the brake pistons are at the same partial vacuum. Assuming that the vehicle brake was originally released, as described above, the brake pistons remain in the bottom position and the brakes remain off. Leaks anywhere on the system allow air to bleed in, reducing or destroying the vacuum. The locomotive will normally carry on sucking whilst the train is in motion to compensate for minor leaks, but more serious leaks must be investigated and corrected before departure. If the engine is creating 21 in/Hg, there must be at least 18 in/Hg at the rear of the train.

The driver applies the brake by partially destroying the vacuum in the train pipe. Operating the brake application valve deliberately allows air into the brake pipe. The further the brake valve is moved, the more air is admitted to the brake pipe. Since the engine is still sucking, altering the position of the valve alters the vacuum in the train pipe.

15 in/Hg is the normal value for initial brake application, 10 in/Hg. is the value for full service braking. Lower values are only applied in an emergency.

Allowing air into the train pipe lowers the vacuum underneath the brake piston, but the vacuum above the brake piston remains at the initial value because of the one-way valve. There is now, say, 21 in/Hg above the brake piston and 15 in/Hg below. The pressure underneath the piston is greater than the pressure above, causing the piston to rise upwards in the cylinder, pulling on the brakes.

As the driver admits more air to the brake pipe, so the differential pressure across the brake piston increases, pulling the brakes on harder. To release the brakes, the driver puts the brake valve back to 'release', stopping the inrush of air and allowing the locomotive to re-create the vacuum in the train pipe and the underside of brake pistons, which rises back to 21 in/Hg. Once again, the same partial vacuum is present on both sides of the brake piston, allowing gravity to make the piston fall and the brakes are released.

In a system as described above, the front brakes are applied before those at the rear, because of the time it takes for air admitted by the driver's brake valve to travel down the train pipe and reduce the vacuum at the rear.

This problem was overcome by the introduction of the Direct Admission Valve ('DA Valve') which is fitted adjacent to each brake cylinder. The DA Valve is a diaphragm valve actuated by the difference in vacuum between the train pipe and the lower part of the brake cylinder. When the driver admits air to the brake pipe to make a brake application, the DA Valve opens on the difference in vacuum between the train pipe and lower part of the brake cylinder. The open DA Valve allows air directly into the lower part of the cylinder until the vacuum in the lower part of the brake cylinder is the same as the vacuum in the train pipe, when the DA Valve closes. Thus, the driver's valve only supplies air to the train pipe: each brake cylinder is directly fed with air under the control of the DA valve on that cylinder and the brakes are applied more quickly. The procedure for releasing the brakes is unchanged.

When a vacuum-fitted vehicle is uncoupled from a train on which the vacuum brake has been previously operative, the train pipe will be open to atmosphere, but there will still be vacuum above the piston, causing the vehicle brake to be applied. You may not rely on this brake, as any leaks will destroy the vacuum above the brake piston and allow the brake piston to fall, releasing the brakes. The brake is said to 'leak off' so you must apply handbrakes or scotches to secure the vehicle. If the braking system is in good condition and air cannot leak past the brake piston, it may be some hours (or even days) before the brake leaks off.

Before the brake has leaked off, it may occur that the vehicle needs to be moved as part of a shunting operation, preferably without having to re-create the vacuum in the train pipe. This is achieved by manually allowing air into the upper part of the brake cylinder so as to equalise the pressures on either side of the piston, allowing the piston to fall and release the brakes. Air is admitted by operating a short lever on each brake cylinder which pushes the ball valve off its seat, letting air past. The lever is attached to a stout cord extending to either side of the vehicle, always called the 'string'. To help you find the string, a star or similar symbol is painted on the underframe adjacent to the string. To release the brake, locate the symbol, reach in and pull the cord hard enough to unseat the ball valve. Keep pulling until you can see that the brake piston is fully down. Remember that bogie vehicles have two brake cylinders and you will need to pull both strings. Vacuum-fitted locomotives are not provided with strings, but some form of release valve will be provided. You must find out the arrangements before you try to shunt a dead engine.

Vehicle brakes work with whatever degree of vacuum the engine can create, but the higher level used by ex-GW locomotives gives a higher available maximum brake effort and better tolerance to leaks before brake force is compromised. A problem arises if a GW locomotive works a train and is then replaced by a locomotive creating only 21 in/Hg. Even when the driver of the GW locomtive destroys the vacuum, 25 in/Hg remains in the upper part of the brake cylinders. When the other locomotive is connected and creates 21 in/Hg, the brakes are not properly released - the difference in vacuum between the upper and lower sides of the piston means that the brakes will be partially applied. The solution is to walk along the train, pulling each string, so that every brake is released. Then, the new engine can create 21 in/Hg which will become the new level of working vacuum in the upper part of each vacuum cylinder.

Tipton Curve Junction Signal Box

In 'Visiting Signalboxes' I described how, in the late '50s and early '60s, I managed to visit (and unofficially operate) a number of mechanical signal boxes in the West Midlands. Most of the notes I made at the time are mislaid, so I'm a bit hazy on chronology.

Geography

Back in the '50s,the Stour Valley Line from Birmingham to Wolverhampton ran through Tipton, where there was a triangular junction with the double-track Princes End Line. The boxes controlling the triangle were Tipton and Bloomfield Junction (both on the Stour Valley Line) and Tipton Curve Junction (on the Princes End Line). Beyond Princes End, the line continued to Wednesbury, where it joined the South Stafford Line. The London and North Western Railway originally provided a passenger service but it can't have been very popular because the passenger service was withdrawn in the 1930s. Although the Princes End - Wednesbury section was built as double-track, it had been singled by the time I knew it but a healthy freight traffic remained.

Traffic

A lot of trains originated at the marshalling yard at Bescot, routed via the South Stafford Line to Wednesbury, then via Princes End to Tipton Curve Junction. Here, the left-hand branch led to Tipton and the South Stour, serving goods depots at Tipton, Albion and Oldbury. The right-hand branch led to Bloomfield Junction and the North Stour, serving the goods depot at Bloomfield Junction, the steelworks at Spring Vale and the steel terminal at Monmore Green. There was occasional traffic to private sidings, like the scrap yard at Deepfields or Mond Gas Sidings near Dudleyport. Princes End signal box still controlled private sidings, like Austin's, but I saw very little traffic to and from there. Tipton Curve had one siding - the 'Tip Siding'. This made a trailing connection with the Down Branch from Tipton to Tipton Curve just short of Tipton Curve box.

The majority of the traffic was probably to and from the steelworks at Spring Vale. The blast furnace required supplying continuously with iron ore, coke and limestone in substantial tonnages. Various minerals were used by the electric arc furnaces to produce special grades of steel. Steel, in various forms, was taken away for use elsewhere. Most of this freight was rail-bourne.

Opening hours

Tipton Curve Junction Signal Box was only open as required. When the box closed, the road was set to and from Tipton and the signals cleared so that trains could run on and off the branch at Tipton. But every train to or from Bloomfield Junction direction required the Porter-Signalman to walk from Tipton to Tipton Curve to open the box. As the name implies, most of the Porter-Signalman's shift was taken up with porter's duties at Tipton Owen Street station, where there was still a substantial parcels sundries traffic. There was often a lady on this duty. Political Correctness had not yet overtaken us and the lady Porter-Signalman was just referred to as the 'Porter-Signalman' or, more often, by the railway slang term 'Porter-Bobby'.

Construction

Tipton Curve Signal Box had been a typical, neat London and North Western all-wooden construction, with a 'Webb' Tumbler Interlocking frame. There was no mains electricity or gas laid-on, so lighting was provided by 'Tilley' paraffin lamps. Some years earlier, there had been a serious fire, which I believe was caused by a 'Tilley' lamp. The operating floor of the box had been completely destroyed. To get the box back in operation, minimum repairs were made to the signalling equipment and an unpainted wooden shed with a sloping roof and a few small windows was stuck over the lever frame. It was the ugliest box I ever worked, and it remained like that until it was abolished when Wolverhampton Power Signal Box was commissioned!

Block Signalling

Absolute Block Signalling was in operation between the signal boxes at Tipton Curve Junction and Tipton Station Box, Bloomfield Junction and Princes End. L&NWR block signalling instruments were used at all these boxes. Tipton Curve also had a Block Switch, to inter-connect the block circuits from Tipton Station and Princes End when Tipton Curve was 'Switched-Out'.

Signals

Signals were upper-quadrant tubular post types. The home signal protecting the facing junction had two dolls - the left stop signal read towards Tipton with a fixed distant for Tipton underneath, the right stop signal read towards Bloomfield Junction with a fixed distant for Bloomfield Junction underneath. This signal was always called the 'four-armer'. There were two home signals reading 'from Bloomfield Junction' and 'from Tipton'. There was also a ground signal controlling movements out of the Tip Siding. Movements into the Tip Siding were controlled by handsignal. There was also a starting signal on the down, towards Princes End. A fixed distant for Princes End was carried underneath the starting signal.

Recollections

Tipton Curve wasn't very busy - there were lots of pauses waiting for anticipated freight trains from Spring Vale which had become delayed awaiting a 'margin' - so I spent lots of time clambering over the frame in the locking room and trying to teach myself about the 'Webb' Tumbler Interlocking frame. For all its perceived defects, it's still my favourite frame.

The Tip Siding was used by the Engineers to dispose of the tons of white sludge produced by the water softening plant at various locations in the area. Water treatment of locomotive boiler water supplies had been introduced extensively by the L.M.S. to reduce maintenance costs. A series of elderly L&NWR locomotive tenders had been converted as sludge tankers. Periodically, the Tipton shunt would arrive dragging a nondescript selection of these vehicles to propel into the siding. All these tenders were loose-coupled, so a rough stop would result in a flood of white liquid sludge being thrown from the filler lids on the tanks - it was advisable to stand well clear! Volunteers on overtime from Tipton would empty the tanks by opening the bottom valves and allowing the sludge to discharge. The siding stood on embankment so, slowly, the 'no-man's land' within the triangle was being filled up. The sludge was a mixture of solid and liquid, so there was a lot of unpleasant, physical work using shovels to clear blockages and remove dried-out sludge.

The 'four-armer' was on an embankment in a fairly bleak spot, close by an abandoned quarry called locally 'The Cracker'. It was not uncommon to open the box for the first time on a winter morning, place the levers back in the frame and discover that the Tipton direction home was frozen 'off'. This meant walking to the 'four-armer', climbing the signal and breaking the ice which had formed overnight.

Near the 'four-armer' there was an underground fire which burned for years. I can remember in winter, with snow on the ground, a clear patch of track near the signal with steam rising!

I had another mishap with the 'four-armer'. The 'Stop' position of an upper-quadrant signal arm is, of course, 'nine o'clock' and the 'Off' position 'ten-thirty'. One day, I pulled off for an approaching freight and was surprised to see the arm go 'over the top' to the 'one o'clock' position because the arm stop had broken!

Oh, and there was the 'Animals on the Line' incident. Princes End Box had received a report of horses wandering about on the line between him and Tipton Curve, which he passed on by telephone. I was working the box unofficially and the signalman had disappeared on an errand somewhere. Bloomfield put a train of empties on the block so I got the road from Princes End but decided I'd have to stop the train and get the driver to examine the line. The curve from Bloomfield to Tipton Curve was vicious, so we always tried to give trains a 'run at it'. I kept my home signal 'On' as the train slowly wound towards me. When he stopped, it was clear that the driver was not best pleased, but there was no help for that. Grudgingly agreeing to proceed with caution, the driver painfully got the train away again. By the time the driver got to the field with the broken fence, the horses had decided that the permanent way offered poor foraging and they'd gone back to their paddock. When the signalman returned, he was amused by my embarrassment at the driver's displeasure. Once we'd confirmed that a temporary repair had been made to the fence, trains could run normally again.

When I first took an interest, most of the freights were steam-hauled by Stanier 'Eight Freights' or 'Fives'. I remember a night-time trip on the footplate of a Stanier Class 8 down the bank to Wednesbury with a raft of empties from Spring Vale. This must have been over twenty years before I started working on the footplate myself in preservation and I found the noise, the heat and the contrast between the blackness outside and the blinding whiteness of the fire fairly terrifying. On another night, I had a similar freight trip, this time on a Brush type 4 (now class 47). I remember the deafening noise from the Sulzer engine behind the cab and being impressed by the four or five thousand amps that the main generator was supplying to the traction motors. The 'Tipton Shunt' engine would occasionally go to Wednesbury with a 'trip' working. This was usually an '03' or an '08' diesel shunter. I had one brake van trip behind an '08' to Wednesbury to pick up a train. But as dieselisation increased and manual signal boxes decreased, I lost interest.

When the electrification of the Stour Valley was in progress, the Princes End Line was often used as a diversionary route for passenger trains at weekends but I can't remember details. I think I only once travelled on a passenger train over the route, on a DMU (this is described in 'A Sunday Stroll to Stafford'). I worked Tipton Curve Box a few times when passenger trains used the line. Because of the fairly sharp curvature between Tipton Curve Junction and Tipton, there was a Local Instruction prohibiting passenger trains from passing on this section and a second passenger train could not be put 'on the block' until the first train was clear.

One 'claim to fame' I remember was when the "largest single load ever carried by British Railways" passed over the Princes End Line en route from John Thompson. This is described here.

I was very lucky to have these experiences which link me to a time so different from the present.